An election worker shows a voter how to use an electronic voting machine in Denver in 2012. (Rick Wilking/REUTERS)

Someone — the Russian military, say many cyber-experts — broke into the computers of the Democratic National Committee and the Democratic Congressional Campaign Committee, releasing emails and sensitive documents. Sounds bad, and is. But a worse danger looms: the possibility that hackers (whether Russians or others) will manipulate our voting machines, casting doubt on the election’s outcome.

Imagine. It’s the day after the election. Either Hillary Clinton or Donald Trump has “won.” But the victor’s triumph rests on close results in five or six states, where the winner had a few thousand more votes. Assume also that each of these states used — at least partially — electronic voting. Assume then that the loser alleges that cyber-tampering stole the election.

The resulting furor would be unavoidable. It would raise partisan anger still further. It would subvert faith in our basic democratic institutions and, probably, excite all manner of conspiracy theories. It would make the combat of the Bush-Gore election in 2000 — the disputes over which of Florida’s “hanging chads” should be counted — look like child’s play. It would be a disaster.

How likely is this cyber crackup? I don’t know, but I’m unwilling to dismiss it totally as a journalistic fantasy for two reasons.

First, this campaign has featured the unexpected and the impossible. The hacking of the Democrats’ computers, coupled with the timing of the release of documents to coincide with the party’s convention, is only the latest example. With apologies to Dave Barry, it can be said of this campaign that “I’m not making this up.”

Secretary of State John Kerry said Tuesday, July 26 that he raised the issue of Russia's involvement in a Democratic National Convention email hacking incident with Russian Foreign Minister Sergei Lavrov on the sidelines of the ASEAN summit. (Reuters)

Second, hacking is more widespread than most Americans think. Big companies are constantly under assault. A CNN study in 2014 estimated that more than 100 million Americans had had their personal information hacked in the previous year. With so much hacking — national and international — why wouldn’t someone try to sabotage the election? In 2012, 129 million Americans voted for president. In a close race (which this appears to be), shifting a few hundred thousand in the popular vote could change the electoral result.

If these thoughts occur to me, a confirmed non-techie, they must have occurred to others. Sure enough, when I Googled the subject, many stories and reports popped up. One of the best was published last week by The Post and was written by Bruce Schneier, a cybersecurity expert at Harvard. He’s worried.

“We must . . . create tiger teams to test the machines’ and systems’ resistance to attack, drastically increase their cyber-defenses and take them offline if we can’t guarantee their security online,” he wrote.

By contrast, there is some good news. Electronic voting machines, which served about 39 percent of voters in 2012 according to one study, may be on the decline. “States ditch electronic voting machines,” read a headline in the Hill newspaper in 2014. (The other main voting technology in 2012, covering 56 percent of voters, involved paper ballots that were optically scanned. The retention of the ballot can be used to verify the outcome. The older mechanical lever machines have vanished.)

Regardless of what happens this year, we are forewarned. Putting voting on the Internet invites controversy and chaos. If we’re lucky enough to avoid this now, we shouldn’t tempt the future. Paper ballots may be “slower and less convenient,” writes Schneier, but they preserve elections’ integrity. What could be more important?

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